* This is a stupid requirement as the quad overdraw shader doesn't use any
interpolators, but the D3D12 runtime complains and refuses to create a PSO
unless the PS has a matching signature. This works as long as the position was
the first output from the previous stage, but if it isn't the PSO fails to
create.
* To fix this, we take the existing shader and patch it by grafting the output
signature from the last stage over onto the input signature, and patching up
where the position is.
* There's not a good accepted terminology for this kind of event, and for
historical reasons 'drawcall' has been the accepted term, even though
that can be quite confusing when a dispatch or a copy is a 'drawcall'.
* This is particularly highlighted by the event browser filters where
$draw() includes draws and dispatches, but $dispatch() only includes
dispatches, it's hard to intuitively understand why $draw() matches all
of these calls.
* As a result we've defined the term 'action' to cover these types of
events in the same way that we defined 'event' in the first place to
mean a single atomic API call.
* The first time a draw is selected bindless feedback runs, ensure the clear-
before-draw overlay works even then. This is a little bit of a hack but it
tests for a known issue.
* We already link to the chunk index and the chunk metadata contains the
callstack, there's no need for a duplicate copy when there may be many
APIEvents in a capture
* For the most part we implement this as a thin pass-through layer. Where we
care about things (image barriers for layout transitions and queue
submissions) we do two different things:
- For image barriers, we "downcast" to plain VkImageMemoryBarrier. Currently
the only thing that's unique to VkImageMemoryBarrier2KHR is extra access
flags and pipeline stages, which we don't care about. This keeps a lot of
code from having to either handle two paths or handle the new path and then
do lots of conversions back to VkImageMemoryBarrier when running on older
drivers.
- For queue submissions we do the opposite. We promote old VkSubmitInfo to
VkSubmitInfo2KHR and process that in a common function, then if necessary
we decay back to VkSubmitInfo before sending to the driver.
* These map more naturally to python tuples and are easier to wrap in and out.
* We also tidy up the FloatVecVal etc and standardise the members of
ShaderValue.
baldurk